198 



THE CELL AND PROTOPLASM 



cause it has a sensitive cortex which on 

 stimulation releases calcium to the interior. 

 This calcium then produces a reaction akin 

 to blood clotting, a reaction which is in- 

 hibited by dilute solutions of fat solvents. 

 The theory that I have proposed has 

 much still to explain. If it is correct it will 

 serve as a guide for the study of the col- 

 loidal interpretation of protoplasmic be- 

 havior. But at best the theory is onl,y a 

 bare outline, and there are huge gaps which 

 remain to be filled in. Each phase of the 

 theory requires amplification, and there 

 are dozens of unsolved problems which 

 stare us in the face. For example we are 

 constantly inquiring as to the mechanism 

 of calcium release from the cortex, and we 

 are also busily trying to interpret various 

 aspects of the clotting reaction, aspects 

 which I did not have time to discuss with 

 you. Moreover, we have hopes of relating 

 calcium release to the electric phenomena 

 which typically accompany excitation. 

 These are but a few of our problems. The 



fact that the theory suggests these prob- 

 lems is a point in its favor. Right or 

 wrong, the theory deserves discussion and 

 test, for at the present time, in view of the 

 recent pajiers which have done much to 

 demolish the experimental support for the 

 permeability theory, there is really no other 

 theory to tie to. 



Eeferencks Cited 



Angerer, C. a. 1936. J. Cellular Comp. Physiol., 

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Churney and Klein. 1937. Biol. Ball., 72: 384. 



Dahlgren. 1915. Carnegie Inst. Wash., Piii. No. 

 212: 213. 



Daugherty. 1937. Physiol. Zool., 10: 4:73. 



Heilbrunn, L. V. 1928; 1937. The Colloid Chem- 

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 General Physiology. Philadelphia. 



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Heilbrunn, L. V. and Daugherty. 1938. Physiol. 

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